Revenge is ours: extracting energy from a cockroach

Scientists show that the sugars stored in the abdomen of some insects can be …

I love science. The joy of discovery in pure research combines with applied science to leave me fantasizing about future technology. Add in the occasional WTF moment and the comedy inherent in poorly prepared presentations, and you have the perfect occupation. Unfortunately, science sometimes attracts people who pull the wings off a cockroach, pin it on its back, and stick electrodes inside it to use it as a mini-electricity generator.

Now, I hate cockroaches as much as anyone, and there is a certain satisfaction in extracting revenge for all those restless nights in rooms that, shall we say, rustled, but... Surely there was a good reason for this?

The basic goal of the research was to see if something like a cockroach could generate enough electricity from stored sugars to power electronic devices. Now, instead of doing what you or I would do—set fire to the cockroach and use the heat to generate electricity—the researcher chose to preserve the life of the insect by employing a redox reaction. The idea being that, with the right configuration, we could get sensors that are both carried and powered by insects, which we could use for all sorts of purposes. This seems like a pretty good reason.

In a standard reaction (like burning something), we are oxidizing one substance and reducing another to release copious amounts of energy. Usually, all the reaction products are in one place. We don't notice that the burning process is, at its most basic, very simple: the transfer of electrons from one molecule to another. Once you realize that, you know that the reaction products can be physically separated, and we can get the electrons to do something useful on the way from one molecule to another.

Sitting inside the cockroach abdomen is a whole lot of sugar waiting to be burned. Outside is a lot of oxygen eager to burn the sugar. The researchers connected the two via electrodes. And, because this highly controlled method of burning requires some help, enzyme catalysts were added at both electrodes.

The result is a tiny amount of power (1 microwatt). But the idea is to get just enough power to drive a few very low-power sensors. Then, combined with a previously developed moth-steering system, we have the perfect spy.

Of course, the fact that the cockroach has to carry around a bottle of enzymes for one electrode is a small disadvantage, but, no doubt, that is something that the researchers are working on. The thing that I find strange about this research is that they also demonstrated that you can get the same reaction and similar power from a dried mushroom. Of course, mushrooms aren't especially mobile. But, considering that the cockroach was pinned down during the experiments and a self-propelled battery was never the intention of the paper, I wonder why they used a cockroach at all?

The only reasonable conclusion is revenge.

Don't get me wrong, I think the idea of insect-powered sensors is a pretty cool idea. It has applications far beyond secret squirrel spy stuff. But I also think that the time to start doing these sorts of experiments is when you are a bit further along the track to a proof-of-principle design.

Chris Lee / Chris writes for Ars Technica's science section. A physicist by day and science writer by night, he specializes in quantum physics and optics. He lives and works in Eindhoven, the Netherlands.